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The polyethylene (PE) coatings could be very promising for various branches of industry due to their chemical stability and impact resistance. Plasma modification of powder has recently attracted much interest because of new prospects to control the interfacial properties. Plasma modification also significantly enhanced the adhesion of the polymer to the substrate. Powders find wide application in various branches of industry like paintings, biotechnology, filling for composite materials etc., but the plasma modification of powder surface has not found such application as plasma modification of flat solid materials. This is due to problems connected with the three dimensional geometry, necessity of solid mixing (due to the aggregation phenomenon) and the large surface area of powders which should be treated. We investigated plasma modification of PE powder, its adhesion properties on steel surface and mechanism influencing this adhesion. PE powder was modified using various working gases and chemicals. It was found that adhesion properties were strongly influenced by concentration of oxygen containing groups and also by PE crosslinking after modification. The value of crosslinking depends on used working gas and chemicals. The ternary mixture of O2/H2O/methanol was found to be an appropriate working gas for plasma treatment of PE for adhesion purposes. The treated PE had good wettability, low crosslinking and very high adhesion to the steel substrate.

Abstract:Tungsten is the prime candidate material for plasma facing components of future fusion devices. Plasma spraying, with its ability to coat large areas, including non-planar surfaces, with a significant thickness, is a prospective fabrication technology for components subject to moderate heat loads, e.g., the first wall of the Demonstration Reactor (DEMO). The functionality of such coatings is critically dependent on their adhesion to the underlying material. This in turn, is influenced by a variety of processing-related factors, chief among them being the state of the interface. In this study, the effects of two factors-surface roughness and the presence of thin interlayers-were investigated. Two different levels of roughness of steel substrates were induced by grit blasting, and two thin interlayers-titanium (Ti) and tungsten (W)-were applied by physical vapor deposition prior to plasma spraying of W by a Water Stabilized Plasma (WSP) torch. Coating adhesion was determined by a shear adhesion test. The structures of the coatings and the interfaces, as well as the characteristics of the fractured surfaces, were observed by SEM.

Abstract. Alloys with various contents of Li were studied by means of differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and energy dispersive X-Ray microanalysis (EDX). The TEM investigations revealed that three different types of precipitation are formed in the alloy matrix during artificial aging. Two of the types represent different morphologies of Mg 2 Si precipitates. The appearance of the third type, identified as the δ-Al 3 Li phase, shows that the Al-Mg-Si system can be used successfully for designing an Li-containing casting alloy. However, this alloy has not yet been developed.